Fluted cutting tool and method of producing a plurality of tools from a single fluted bar



Dec. 16. 1969 E. F. FABISH FLUTED CUTTING TOOL AND METHOD OF PRODUCING APLURALITY OF TOOLS FROM A SINGLE FLUTED BAR Filed July 1, 1968 INVENTQRQEdward E Fab/sh BY V3 C2 His Aff'ys United States Patent 0 3,483,605lFLUTED CUTTING TOOL AND METHOD 6F PRO- DUCING A PLURALITY 0F TOOLS FROMA SINGLE FLUTED BAR Edward F. Fahish, Glenview, Ill., assignor toIllinois Tool Works Inc., Chicago, 111., a corporation of Delaware FiledJuly 1, 1963, Ser. No. 741,415 Int. Cl. B26d 1/12 U5. Cl. 29-103 4Claims ABSTRACT OF THE DISCLUSURE Throw away cutting tool such as endmill has short, tapered shank adapted to be held in correspondinglytapered holder. A plurality of cutting tool blanks can be produced froma single length of bar material by first forming at least three flutesin the bar and then tapering and cutting off individual blanks in anautomatic screw machine. The cutter blanks are finished by hardeningthem and then sharpening their cutting surfaces while holding them in atapered holder.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to fluted cutting tools and more part cularly to an improvedcutting tool and method for making a plurality of such tools from asingle fluted bar.

Description of the prior art Tools having rather short tapered shankswhich are adapted to be held in correspondingly tapered holders areknown in the prior art as exemplified by US. Patents 1,461,548 and2,283,514 to C. A. West and A. Stanworth, respectively. These patentspoint out that the cost of such tools may be reduced considerably overconventional tools since they utilize a relatively small amount ofcostly high speed or special alloy steel. The savings in material ispossible due to the fact that the holder may be made of less costlysteel or other material than the cutters.

Although tools of the type just mentioned do result in lowermanufacturing costs due to savings in the cost of materials, suchsavings in materials are not particularly significant unless the laborrequired to manufacture the tool can also be reduced considerably.Because the prior art tools which are adapted to be used as inserts inholders are generally made by the same methods used to make ordinarytools which are self supporting, it has not heretofore been possible toachieve a true throw-away tool which can be produced at a costsignificantly lower than an ordinary tool such that it would be moreeconomical to replace the tool with a new one than to resharpen it.

Although the concept of manufacturing a plurality of twist drills from asingle piece of bar stock by heating the bar, mechanically working it toform longitudinal flutes in it and then twisting it is shown in US.Patent 2,457,132 to H. W. Delaney, this teaching could not produce thecutter blanks produced by the process of the present invention.

SUMMARY It is an object of this invention to provide a fluted cuttingtool which may be produced quite economically and which, although it canbe resharpened in the same manner as a conventional cutter, can be soldfor a cost sufliciently low that it would, in many cases, be moreeconomical to throw away the cutter without resharpening than topurchase a conventional cutter and resharpen it.

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It is another object of this invention to provide a fluted cutter whichhas portions of its land areas between its flutes which extend into itsshank portion and serve as surfaces for supporting the cutter in atapered holder into which the shank is inserted.

Still another object of this invention is to provide a method of makinga plurality of tapered shank cutter blanks by mounting a long fluted barof material in a tapering and cutting device such as an automatic screwmachine which progressively tapers the shanks of, and cuts off theindividual blanks. Such blanks can then be hardened and sharpened tobecome commercially suitable cutting tools.

These objects are obtained by the cutting tool and method of the presentinvention. The cutting tool, which is preferably an end mill, includesside and end cutting portions and a shank portion adapted to be receivedin a socket or holder member. The cutter is held in the socket member bya retaining means such as a set screw which is threaded through thesocket member and presses against a notched surface on the shank of thecutter for driving the cutter axially into tighter and tighterengagement with the socket member and for preventing rotation relativethereto. The socket member is adapted to be mounted in and driven by thechuck of a milling machine and for this purpose may include a Morsetaper shank although obviously, other driving configurations could beused.

The cutting tools are formed from blanks which are cut off from a lengthof fluted bar material such as high speed tool steel. The steel bars arepreferably fluted along their entire length. Although a 25 inch bar hasbeen found satisfactory, any length bar can be used depending upon thecapacity of the forming apparatus employed. The fluting may take placein a variety of ways such as by grinding, milling, rolling or forging.The flutes preferably have a constant helical lead and a constant rootdiameter throughout the length of the bar. After the bar is fluted it ispreferably placed in a long support collet in an automatic screwmachine. The collet preferably has a length considerably longer than thediameter of the bar since the bar is only supported on the relativelynarrow land areas which are formed between the flutes and whichconstitute the outer diameter of the surface of the bar. In

order to produce a cutter blank, a short length of the fluted bar ismoved outwardly through the collet against a stop member. As the bar isrotated, a tapered turning tool is moved radially inwardly to the end ofthe bar until the terminal end of the shank is formed at which time thetapering tool is moved in an axial direction toward the collet andradially outwardly of the bar. A second forming tool is used to cut offthe cutter blanks from the remaining stock in the collet. To achievemaximum production the cut-off tool may operate simultaneously with thetapering tool.

After the cutter blank is formed, it is then hardened, heat treated andsharpened in a holder having a taper corresponding to the shank paper.The retaining notch is preferably formed in the tool shank afterhardening.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of afinished cutting tool of the present invention showing the cutting toolin locked position in an appropriate holder having an elongated taperedshank;

FIG. 2 is a perspective diagrammatic showing which illustrates themethod step of forming flutes in a long piece of round bar stock bygriding;

FIG. 3 is a top plan view which diagrammatically illus trates theadditional method steps of tapering and cutting off individual toolblanks from a long piece of fluted bar material formed in accordancewith the method of FIG. 2;

FIG. 4 is an edge plan view of the grinding wheel and a cross section ofthe rod shown in FIG. 2 showing the shape of the flutes;

FIG. 5 is a perspective view of the finished cutter shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, a finished cuttingtool indicated generally at and having a cutting portion 12 and a shankportion 14 is shown mounted in a socket or holder member 16. A taperedshank surface 18 on the cutter 10 corresponds with a similarly taperedsurface 20 on the inside of socket member 16 to firmly engage and centerthe cutting tool 10. The angle chosen for surfaces 18 and 20 can bevaried depending upon the degree of locking which is desired. Byutilizing taper angles less than about 7 /2 degrees it has been foundthat locking of the shank 18 to the holder 16 will take place so as tonecessitate the provision of either an axial or radial hole through theholder 16 to permit the insertion of a drive pin (not shown) forknocking out the cutting tool when it must be replaced or resharpened.'By utilizing a taper angle over 7 /2 degrees, the cutting tool andholder will not firmly lock together and the cutting tool may easily bereleased by tapping the holder. A taper angle of 11 degrees for thesurfaces 18 and 20 has been found particularly satisfactory. Thecuttingtool 10 is held in rigid engagement with the socket member 16 bya retaining means such as a set screw 22 which is in threaded engagementwith holder 16 and which engages a notched surface 24 in the shank 14.The notched surface 24 is preferably formed at an angle which will causethe set screw 22 to exert an axial component of force on the shank tohold it in the socket and also prevent its rotation in the socket. Thesocket or holder member 16 is provided with a conventional shank such asa Morse taper shank 26 including a tang portion 28 which may be insertedin a milling machine chuck for driving the cutter tool.

The cutting portion 12 of the cutting tool 10 includes a plurality offlutes 32, and preferably three or more reasons to be describedhereinafter. The flute portions 32 are separated from each other by landportions 34 including longitudinally extending cutting edges 36. Thelongitudinal cutting edges 36 are side cutting edges which coact withend cutting edges 38 to permit the cutter to be moved transverselythrough a piece of material to be cut (not shown) so as to form slotstherein or to otherwise remove material therefrom.

The cutting tool 10 is relieved at an intermediate portion 40 thereofwhich separates the shank portion 14 from the cutting portion 12. Therelieved portion 40 insures that the side cutting edges 36 are clearlydefined in relation to the remainder of the land portion 34 whichcontinue from the cutting portion 12 of the cutter into the shankportion 14. This relieved portion 40 also provides clearance for thegrinding wheel used to sharpen cutting edges 36.

As can be seen in FIG. 1, the flute portions 32 continue from thecutting portion 12 of the cutter into the shank portion 14. It will benoted that the flutes 32, which have a constant root diameter, becomeprogressively narrower as they proceed along the shank portion 14 from apoint 32a at the intermediate relieved portion 40 to a point 3212 at theterminal end portion 42 of the shank wherein they disappear due to thediameter of the shank becoming reduced below the root diameter of theflutes. Necessarily, the land portions 34 become progressively Wider asthey proceed along the shank from point 34a to point 341).

Since the narrow land portions 34a provide much of the shank area whichsupports the tool in its socket or holder, it is important that thesupport be as firm as possible. By providing three or more spaced landportions on the tool shank the shank is able to provide a firm and 4equal support for the tool. If only two lands were provided the toolcould possibly rock in its holder.

FIG. 2 diagrammatically shows one step in my method of forming thecutter shown in FIG. 1. An elongated piece of bar material indicatedgenerally at 46 which preferably has a circular surface 48 is movedaxially and rotationally relative to a forming means such as thegrinding wheel 52 to produce a plurality of flutes 32 which have aconstant angle of lead and a constant root diameter. The particularstructure used to mount the bar 46 for grinding the flutes is not shownsince it is conventional and forms no part of the present invention.Such a grinding structure would of course include means for engaging oneend of the bar 46 and rotating it while moving it axially relative tothe grinding wheel. In tests, satisfactory fluted bars have beenproduced by utilizing a 25 inch length of bar stock and cutting flutestherein which have a 30 degree helical lead by means of a grinding wheelhaving its plane of rotation positioned at a 34 degree angle to the axisof the bar 46.

In FIG. 3 the fluted bar 46 produced by the method step depicted in FIG.2 is diagrammatically shown as mounted in a collet 56 which is supportedin a chuck 58 of the type typically found in an automatic screw machine(not shown). A stop member (not shown) on the automatic screw machinemay be used to permit an exact length of the bar 46 to be fed outwardlyof the collet 56. Once the stop is engaged, the bar 46 is turned while atapering tool 62 is moved radially into the terminal end of the shank 14and then moved axially toward the collet and radially outwardly of thebar 46 until intermediate portion 40 is reached at which time the tapertool 62 is withdrawn. Either following the operation of the taperingtool 62, or simultaneously therewith, a cut-off tool 64 is movedradially inwardly of the rod 46 to cut off the tapered tool blankindicated generally at 66.

FIG. 4 is a view of the side edge of the grinding wheel 52 which hasbeen dressed to provide the flute shape shown in FIG. 2. By dressinggrinding wheel 52 so that the side and end surfaces 72, 74, 76 haveangles of approximately 70 degrees, 12 degrees and degrees from the axisof the grinding wheel it is possible to secure the flute surfaces 82,84, and 86 shown in FIG. 2.

The cutter blank 66 which is severed from the bar 46 in FIG. 3 must haveadditional steps performed on it before it becomes the finished cuttingtool 10 shown in FIGS. 1 and 5. These additional steps include the stepsof hardening and heat treating followed by a sharpening operation. Thehardening and heat treating operations are conventional and need not bedescribed herein. Sharpening of the cutter blank 66 to form cuttingedges 36 is accomplished in a commercially available sharpening fixturesuch as, for example, a fixture similar to that disclosed in US. Patent2,569,855 issued to Carl J. Hertlein. During sharpening, the tool blank66 is inserted in a holder (not shown) having the same taper as thetaper 20 on holder member 16 and is moved axially and rotationally pasta grinding wheel (not shown), To guide the tool as it is sharpened, afixed guide member (not shown) in the fixture bears on a side of a fluteat all times.

It will be readily seen that the method just described will enable alarge number of cutting tool blanks to be formed from a single flutedbar. Although naturally, the time required to form the flutes in a longbar is much longer than that necessary to form the flutes in a singlecutter, there are great savings in the amount of time required to mountthe member to be fluted.

I claim:

1. A cutting tool having a short tapered shank at the rear terminal endthereof adapted to be held in a correspondingly tapered socket member,said cutting tool comprising at least three flute portions, each of saidflute portions having a constant lead and a constant root diameter andextending along substantially the entire length of said tool wherein theouter diameter of said tool exceeds said constant root diameter, atleast three land portions on said tool comprising the peripheral surfaceof said tool between said flute portions, said land por tions includinglongitudinally extending cutting edges defining a side cutting portionof said tool, the terminal end portion of said tapered shank having areduced diameter less than said constant root diameter of said fluteportions, said tapered shank extending from an intermediate portion ofsaid tool adjacent said side cutting portion to said rear terminal end,the peripheral surface of said tapered shank comprising relativelynarrow land portions separated by relatively wide fiute portions at theintermediate portion of the tool and comprising progressively wider landportions and progressively narrower flute portions along the length ofthe shank to the terminal end portion of said shank, at which portionthe surface of said shank becomes smooth and uninterrupted.

2. A cutting tool as defined by claim 1 and further comprising retainingmeans integrally formed on said tapered shank for permitting saidcutting tool to be firmly and non-rotatably held in a correspondinglytapered socket member having cooperating retaining means.

3. A cutting tool as defined in claim 1 wherein said cutting tool is anend mill and includes a plurality of front cutting edges formed on thefront terminal end thereof, said front cutting edges intersecting withsaid longitudinally extending cutting edges so as to define the cuttingportion of said end mill, the lands defining the tapered shank surfaceof said tool at the intermediate portion of said tool being of lessdiameter than the adjacent land portions on which said longitudinalcutting edges are formed.

4. A cutting tool as defined in claim 3 wherein the tapered shanksurface of said cutting tool is notched so as to provide a retainingsurface lying in a plane transverse to the angle of taper, one surfaceof said notch being adapted to receive a fastener positioned in a socketmember for driving the tapered shank axially into firm engagement withthe walls of the socket member While preventing rotation of the cuttingtool relative to the socket member.

References Cited UNITED STATES PATENTS 1,424,392 8/1922 Baker et al29103 1,461,548 7/1923 West 2799 1,505,977 8/1924 Stanworth 29103 X1,931,684 10/1933 Aker 51--288 2,150,189 3/1939 Ronneberg 279-83 X2,283,514 5/ 1942 Stanworth 279-83 2,457,132 12/1948 Delaney 72642,923,053 2/1960 Babbitt 29103 HARRISON L. HINSON, Primary Examiner U.S.Cl. X.R. 5l288; 279-83

